In an Internet protocol (hereinafter referred to as IP) bearer network, packet loss is one of important measurement indexes for quality of service (Quality of Service, hereinafter referred to as QoS).
Packet loss detection may be performed in various manners, where an existing packet loss detection manner is detection based on the counting of service packets. In a method of detection based on the counting of service packets, the number of lost packets may be calculated according to the number of service packets that are received by a receiving end before the receiving end receives a detection packet. For example, within one counting period, a sending end sends four service packets, and then sends one detection packet. For the receiving end, the counted number of received packets is the number of the service packets before the detection packet is received. If three service packets are received before the detection packet is received, the number of lost packets is 4−3=1.
However, when a packet transmitting path is a load sharing multipath, or QoS scheduling exists in a packet transmitting device, a disorder may occur, that is, a sending end sends packets in order, but this order changes when the packets reach a receiving end. For example, the foregoing sending end first sends a service packet and then sends a detection packet; while at the receiving end, a case that first the detection packet is received and then the service packet is received may occur, which causes that during calculation of the number of lost packets, a service packet received after a detection packet is not counted, so that the calculated number of lost packets is inaccurate.